1. Field of the Invention
The present disclosure relates to a flow passage assembly having a plurality of flow passage forming members stacked therein and a flow passage between every two neighboring ones of the flow passage forming members, and a method for manufacturing the flow passage assembly, an inkjet recording head, and a recording apparatus.
2. Description of the Related Art
A typical liquid ejection head for ejecting liquid is an inkjet recording head (hereinafter also simply referred to as a “recording head”). Full line recording heads have ink nozzles arranged in a range corresponding to the width of the recording medium in a direction perpendicular to a direction in which the recording medium is conveyed. Japanese Patent Laid-Open No. 2008-87465 describes a recording head including a flow passage that supplies ink thereto, a circulation flow passage, and a flow passage used for removing a bubble existing in the flow passages.
In addition, Japanese Patent Laid-Open No. 2007-283668 describes a flow passage assembly including a flow passage capable of leading liquid, such as ink, in a predetermined direction. The flow passage assembly described in Japanese Patent Laid-Open No. 2007-283668 has a structure including a first flow passage forming member having a second flow passage forming member stacked thereon.
The top surface of the first flow passage forming member of the flow passage assembly has a flow passage groove formed therein. The flow passage groove serves as a flow passage. A welding rib is formed on either side of the flow passage groove so as to extend along the flow passage groove. The bottom surface of the second flow passage forming member has a groove that receives the welding rib of the first flow passage forming member when the flow passage forming member is stacked on the first flow passage forming member. The welding rib of the first flow passage forming member is welded into the groove of the second flow passage forming member using an ultrasonic welding process.
If the first flow passage forming member and the second flow passage forming member are welded together in this manner, the flow passage groove of the first flow passage forming member is sealed with the bottom surface of the second flow passage forming member. Thus, the flow passage groove of the first flow passage forming member can function as a pipe-shaped flow passage capable of leading liquid, such as ink, along the flow passage groove. As described above, in the flow passage assembly described in Japanese Patent Laid-Open No. 2007-283668, by stacking the second flow passage forming member on the first flow passage forming member, a flow passage is formed between the first flow passage forming member and the second flow passage forming member.
In the flow passage assembly described in Japanese Patent Laid-Open No. 2007-283668, only the second flow passage forming member is stacked on the first flow passage forming member. In addition, a third flow passage forming member may be stacked on the second flow passage forming member.
In a flow passage assembly having such a structure, the top surface of the second flow passage forming member has a flow passage groove and welding ribs that are similar to those of the first flow passage forming member formed therein. In addition, the bottom surface of the third flow passage forming member has a groove that is similar to that of the second flow passage forming member formed therein. Furthermore, the welding ribs of the third flow passage forming member are welded into the groove of the first flow passage forming member using an ultrasonic welding process.
In such a flow passage assembly, a flow passage is additionally formed between the second flow passage forming member and the third flow passage forming member. In this way, two flow passages that are arranged in a vertical direction are formed in the flow passage assembly. Since the flow passage assembly includes a plurality of flow passages, the flow passage assembly can independently lead a plurality of types of liquid, such as ink, at the same time.
However, if, as described above, the flow passage assembly including a plurality of flow passages is used for a recording head, the size of the flow passage assembly is increased.
In addition, in order to manufacture the above-described first flow passage forming member, second flow passage forming member, and third flow passage forming member, the welding ribs of the first flow passage forming member are welded into the groove of the second flow passage forming member using an ultrasonic welding process in a first manufacturing step. Subsequently, in a second manufacturing step, the welding ribs of the second flow passage forming member are welded into the groove of the third flow passage forming member using an ultrasonic welding process.
Accordingly, in the second manufacturing step, the welding rib of the first flow passage forming member that is welded in the preceding step may happen to partially come off from the groove of the second flow passage forming member due to the load caused by, for example, vibration occurring when the welding ribs of the second flow passage forming member are welded into the groove of the third flow passage forming member.
Alternatively, in the first manufacturing step, the welding ribs of the second flow passage forming member may be welded into the groove of the third flow passage forming member. Subsequently, in the second manufacturing step, the welding ribs of the first flow passage forming member may be welded into the groove of the second flow passage forming member. However, in such a case, in the second manufacturing step, the welding rib of the second flow passage forming member that is welded in the first manufacturing step may happen to partially come off from the groove of the third flow passage forming member due to the load imposed when the welding ribs of the first flow passage forming member are welded into the groove of the second flow passage forming member.
As described above, in the flow passage assembly having the welding rib that comes off from the groove, liquid, such as ink, that flows through the flow passage leaks out of the portion at which the welding rib comes off.